Question

已知2分之a=3分之b不等于0,求代数式a的平方-4b的平方分之5a-2b乘以（a-2b）的值

Answer 1

∵a/2=b/3≠0
∴设a=2k，b=3k
(5a-2b)/(a²-4b²)×(a-2b)
=(5a-2b)(a-2b)/(a+2b)(a-2b)
=(5a-2b)/(a+2b)
=(10k-6k)/(2k+6k)
=4k/(8k)
=1/2

Answer 2

2分之a=3分之b
∴a=2b/3

a的平方-4b的平方分之5a-2b乘以（a-2b）
=(5a-2b)/(a+2b)(a-2b)×(a-2b)
=(5a-2b)/(a+2b)
=(10b/3-2b)/(2b/3 +2b)
=1/2